Grid for protecting rontgen images against secondary rays



Dec. 4 1923.

' G. BUCKY GRID FOR PROTECTING RO'NTGEN IMAGES AGAINST SECONDARY RAYSFiled May 17, 1923 :rsumal JEUREE.

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Application filled ma 17, was. Serial no. sweet.

To all who m am concern I Be it blown t at I, GosrAv Boom, a citizen ofthe German Empire, residing at Berlin W., Germany, have invented certainnew and useful Improvements in Grids for Protectin Rontgen ImagesAgainst Seconda plication for 15th day of 104,821 a ilication. 7

he secondary Rdnt-gen rays that arise,

atent in 'Germany on the ay, 1922, application Nr. B

when Rontgen rays pass through a body exposed to them for purposes ofphotography, bring about a blurred efiect in the hotos made by the'prima Rontgen rays. is blurred efiect has heretofore been avoided byintercepting the secondary rays by means of a grid, d1sposed (almost)impervious to Rontgen rays. This grid being fixed between the body andthe photographic late and having passages extending in the irection oftravel of the primary rays.

Although this was a great lmprovement with regard to the clearness ofthe photos taken es ciall of soft parts of the body 1H; 'de n the cleaed shadow that'the grid threw on the" fluoroscopic screen or hotographicplate was considered a drawback. And therefore in fluoroscoping the gridwas sometimes shifted, in order to expose to the X-rays the partotherwise shielded therefrom. In taking photos the same; course wasfollowed in order to at rid ,of the troublesome grid shadow as ar pose,Iemploy a 1t wigs nec'esary as possible. But in order to. avoid gettingphotos showing stripes due to the shadows,

to shift the grid atperlar intervals, which could only one y amechanical contrivance, for instance, a sprin motor or an electricmotor. Such a device must of course increase the amount of attendance ruired or if considerfectl re oordin to the invention by using astationary gri the shadow of the grid, so annoying to an observerafterward examining the photo, is done awa with. For this purof suchfinetexture that the stripes or es left by the shadows of those parts of thegrid that are imrv 1ous to R6nt%n rays, arescarcely discennble the na edeye, their effect beifi so httle, in fact, that they become blend lgmone'expensive. c

ays (for which I have filed ap IX/30a),of which the following is' andappear as a kind of light veil. Thus in my evice, without moving thegrid, the

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same efiect' is brought about on the photo'- I gra hic plate asheretofore a uniform shi ting of the grid would produce. If afluoroscopic screen be .used instead of the photographic plate, of theobserver an image of the sort just described. .However, ifthe movablegrid heretofore known be used, for either the photographic plate or thefluoroscopic screen, there can still be discerned, on such plate orscreen, the troublesome image reembling a net or sieve. t

The new grid can be made in difierent wa s.

igure 1 is a diagram, showing one form of m an -ray tube.

Figure 2 is a fragmentary elevation showing a portion of the gridappearing in Figuri 1, but upon an enlarged scale.

1 showing another form of grid made in ac-' cordance with my invention.

Figure 4 is a fragmentary perspective,

it present to the eye invention as used'in connection with.

I re

re 3 is a fragmentary perspective,

showing still another form of grid made in covered with material Jbundle, and in this form are pressed while subjected, if'necessary, towarmth. In this way is formed a mass of material which sticks togetherfirml and which contains the wires 5, im edded and disposedsubstantially arallel with each other, so as to permit "ntgen rays topass through it easily. From the mass thus produced slabs are cut offand bent to spherical curvature, so that the radius of curvaturecorresponds exactly with the distance between the focus of the Riintgenray tube and the screen.

In Figure 1 is shown a grid 7, madeao just described and positioned aabove stated relatively to an X-ray tube, which p rs a 8,

proved grid is by placing alternate A source of secondary Rontgen raysis shown at 9.

The radial directions of travel of the primary rays are indicated byconventional lines 10, and the directions of travel of the secondaryrays are similarly indicated by lines 11.

It will be noted'that with the grid thus constructed and arranged, the'imbedded wires 5 extend len thwise in the directions of travel of theprimary Rontgen rays, but that the secondary Rontgen rays areintercepted.

In Figure 3 I show another form of my improved grid made in a simplerway. This grid comprises a number of thin leaves 12, of metal of suchcharacter as not to be very pervious to Rontgen rays. These metallicleaves 12 are severally coated on one or both sides with lacquer orother analogous substance, such as becomes sticky when exposed to ahightemperature. The leaves thus coated are placed one on top of the other,and pressed together while exposedto heat.

From the mass thus produced, as shown in Figure 3, a grid is made up, asindicated at 7 in Figure 1. extreme fineness of the wires and the verysmall distance between them the total efiect of the shadow is not moreannoying than that of a fine sieve in an auto-type.

' Another method of preparing Hi imlayers of thin leaves of metalimpervious to Rontgen rays and celluloid leaves and sticking themtogether by using pressure.

This method may be understood by reference to Figure 4 in which is showna number of leaves 14 of metal impervious to Rontgen rays, alternatedwith a number of leaves 15, of celluloid. The leaves are all stucktogether, under pressure.

In making the grid made as just described and as shown in Figures 3 andt,

In consequence of the.

rare-pea the mass must be so cut that thehplates J extend at ri htangles to the general direction of the at layer or mass, and the platesthus formed should thenbe bent cylindrically. The curvature of thesurface of the grid thus formed should be chosen according to thedistance to be-used from the Rontgen tube to the grid, so that the focusof curvature of the id will coincide with the" source of the ontgenrays; and so that the individual metallic leaves or sheets extendedgewise in the directions of travel of the primary rays.

Claims for patent: v i

1. The method herein described of constructing a Rontgen ray grid, whichconsists in bringing together a. number of leaves of metal of highatomic Weight and a number of leaves of material relatively transparentto Rontgen rays and to which said leaves of metal can be made toadhere,said leaves of metal being alternated with said second mentioned leavesand being so thin and close together that an image made by them whenthey are stationary appears to the eye as practically uninterrupted, andcausing all of said leaves to adhere together as a unitary member.

2. A grld for transmitting primary I lltontgen rays while substantiallypreventing the passage of secondary rays, consist- GUSTAV BUCKY.

In testimony whereof I afix my signature.

